Bickerstaff Brainstem Encephalitis Presenting With Negative Anti-GM1 and Anti-GQ1B Antibodies.

A woman in her 60s initially presented with rapid-onset left-sided hemiparesis with later development of slurred speech and left-sided facial droop. Despite ruling out common causes, her condition rapidly progressed with the development of bilateral proximal weakness, ophthalmoplegia, ataxia, and pyramidal signs eventually leading to a cardiorespiratory arrest. Extensive investigations, including computerised tomography (CT), magnetic resonance imaging (MRI), and lumbar puncture (LP), were negative for infectious or vascular aetiologies.